(1) Field of the Invention
The present invention relates to a grinding machine for cutters used in wood working machines such as superfinishing wood planing machines.
(2) Description of the Prior Art
Cutters used in wood working machines such as superfinishing wood planing machines have to be sharpened precisely.
Japanese Patent Publication No. Sho 47-42590 discloses a cutter grinding machine which comprises a carriage being disposed laterally movable on a bed; a cutter holder being provided on said carriage, to which holder a cutter is attached from above so that its ground surface is horizontal; a vertical strut being provided at the rear of said carriage; a turning member being fitted to said vertical strut; a grinding wheel and a lapping wheel being respectively attached vertically movable to said turning member; either of said grinding wheel and lapping wheel being selectively brought into contact with the cutter by the turn of said turning member so as to perform the grinding and lapping of the cutter alternately.
The grinding wheel, etc. are worn down by grinding operation. Furthermore, the grinding wheel and the lapping wheel differ from one another in the quantity of wear because they are different in hardness and frequency of use.
In the grinding machine of the prior art, whenever such difference in the amount of wear has appeared, it is necessary to adjust the positions of the grinding wheel and lapping wheel manually by means of hand wheels while watching them. However, it is very troublesome to do so, and furthermore, it is difficult to keep the extent of the grinding or lapping constant.
There has also been a grinding machine in which the vertical movement of each grinding wheel is performed semi-automatically. That is, the grinding wheel is moved down to a position proximate to the cutter by a vertically driving device, but the operator has to confirm the proximate position visually and stop the vertically driving device, then he has to lower the grinding wheel manually until it comes into contact with the cutter. However, this semi-automatic grinding machine has the disadvantage that the position of each grinding wheel has to be readjusted often and manually, because it is worn down by grinding operation. Therefore, the efficiency of operation is reduced.